IF Patrick Ewing, the self-proclaimed best center in the East, wears The Emperor’s Clothes at age 37, he came to Game 3 last night dressed with a scowl.

Criticized in the media, pilloried on sports talk radio, Ewing brought to the Garden a .325 shooting percentage and a lip, rolling his eyes when Chris Childs failed to deliver the ball on demand eight minutes into the third quarter, shaking his head after finally receiving the ball and scoring his second field goal of the game.

Up against age, back pain, and again, Alonzo Mourning, Ewing never figured to be able to outrun his age, now is losing ground on his critics. His chances of getting even dwindling, he is getting mad. With 2 seconds left, and the Knicks down two, he lined up all his doubters, and told them to drop dead with a 17-footer that saved the Knicks an overtime.

In that overtime, he dribbled the ball off his foot and out of bounds with 59.7 remaining. Then, fouled by Dan Majerle as he attempted his final drive on Mourning, missed the first of two free throws, leaving the game hanging over Anthony Carter’s hanger, which caught rim, bounced high and came down for a 77-76 Miami win and a 2-1 series edge.

A goaltending call on Mourning by Hue Hollins was overruled by Dan Crawford. The ball dropped through clean, no payback yet for Allan Houston’s good fortune last year in Game 5, but enough to put the Heat halfway to the sweetest series victory of their lives.

Ewing went hero to bumbling goat, his lack of discretion beating his valor down the open floor again. He didn’t have to outplay a younger, stronger, opponent start to finish, only had to do the right things at the right time and ultimately didn’t get it done.

Mourning, with 15 points and five rebounds at the half, on the way to a monster performance, picked up three fouls in 26 seconds before three minutes had been played in the third quarter, but the Knicks, who extended the lead to 49-42 on a Ward drive, still couldn’t shake the Heat. Continually freeing up baseline jumpers, Clarence Weatherspoon and P.J. Brown and Jamal Mashburn brought Miami back.

Mourning came back in with 7:59 to play, dropped in 5-footer off a pass from Dan Majerle to put Miami up 62-59. He dove to the floor to strip Latrell Sprewell trying to corral a defensive rebound, retreated out of a double-team to knock down a 16 footer to make the lead 66-63. He arched backwards from along the baseline to grab a Mashburn miss, was fouled trying to put the ball back up, and hit the two free throws. In the overtime, he hit a baseline jumper to tie the game at 75.

“As long as my contribution helps us win, I’m not worried about having any monster game,” Mourning said before the game. Less is more sometimes, Game 2 being the most recent example. “At times, I forced the issue a little bit in Game 2.

“At certain times during the game I shouldn’t be putting myself in position where I gotta force the issue. Those were shots I was making all year, but I know what my high percentage shot is and that’s taking it right to the bucket. That’s a matter of making the proper adjustments, taking what the defense gives me.”

Thus did Game 3 begin last night, with the series strapped on his back. “He’s gotta play an all-around game for us, we know that,” said Pat Riley. “[But] somewhere one of our guys other than Zo or [Mashburn] will step up big time.”

Brown, with 14 points mostly off baseline jumpers, and Weatherspoon, who had his nine points while Mourning spent 12 long minutes on the bench, did. With Tim Hardaway a shell of the threat he used to be, with Mashburn the only other Miami player capable of making his own shot, the Heat had to execute its offense crisply, and Mourning couldn’t fry in the heat at the end. The more attention the Knicks have to pay him, the more functional Miami’s offense becomes, the more the Heat can exploit Ewing, who looks eminently exploitable.

“I don’t want Larry to guard [Mourning], either,” said Van Gundy before the game. “P.J. Brown gets points on second chances and Patrick has never been a great block-out player. And we need to block out.

“Kurt does all right against Alonzo, but he’s not going to get the benefit of calls. Mourning can shoot over Kurt and Larry, but we have a better chance of guarding the dribble.”

In other words, the Knick coach has a choice between strychnine and hemlock.

“It’s still Patrick’s time,” John Thompson, who coached both players at Georgetown, has said about the results of past meetings.

But Ewing is looking past his time and Mourning overdue for the kind of playoff game that finally lifts his team on his back. The Heat, as currently constituted, is a load for anybody, but Mourning appears able to handle it.